Methods of making blend compositions of an unmodified polyvinyl alcohol and metallocene polyolefin or a grafted metallocene polyolefin

ABSTRACT

This invention relates, in general, to methods of making blend compositions of an unmodified polyvinyl alcohol and a metallocene polyolefin or grafted metallocene polyolefin and thermoplastic film and fiber structures comprising these blend compositions. More specifically, this invention relates to methods of making substantially water-free films and fibers comprising unmodified polyvinyl alcohol and a metallocene polyolefin or grafted metallocene polyolefin.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 09/464,625, filed Dec. 16, 1999 now U.S. Pat. No. 6,203,903,which is a division of U.S. patent application Ser. No. 09/088,352,filed Jun. 1, 1998, now U.S. Pat. No. 6,020,425.

FIELD OF THE INVENTION

This invention relates, in general, to methods of making blendcompositions of an unmodified polyvinyl alcohol and a metallocenepolyolefin or grafted metallocene polyolefin and thermoplastic film andfiber structures comprising these blend compositions. More specifically,this invention relates to methods of making substantially water-freefilms and fibers comprising unmodified polyvinyl alcohol and ametallocene polyolefin or grafted metallocene polyolefin.

BACKGROUND OF THE INVENTION

Personal care articles are widely used in today's society. Many of thesearticles use films and fibers that are thermoplastic. Additionally,these articles use films and fibers that have different properties,depending on their location in the product. For example, some films andfibers are elastomeric. Others are breathable while still others act asliquid barriers. Finally, some of the films and fibers, especially thosein contact with the wearer of the product, are designed to be softer tothe touch. These different films typically comprise polymers or polymerblends that, when processed, form a film or fiber having the desiredcharacteristic or characteristics.

Additionally, in an attempt to deal with decreasing land-fill and solidwaste disposal many of these films and fibers are designed to bewater-dispersible such that the product will partially or completelydisperse in water, thereby allowing the product to be disposed ofwithout dumping or incineration. These products may be placed in sewagesystems or may be flushed down a conventional toilet. To produce thesewater-dispersible products, the films and fibers used in the productswill typically use blend compositions that include a water-dispersiblepolymer such as polyethylene oxide or polyvinyl alcohol.

Polyvinyl alcohol (PVOH) is a commodity polymer that is used in a widevariety of different applications. Many of these applications arethermoplastic. However, PVOH is generally regarded as anon-thermoplastic polymer. PVOH has a high melting point of about 200°C. depending on the degree of hydrolysis. Accordingly, as PVOH is heatednear its melting point, yellowing and discoloration occur. Therefore,when using PVOH as a base material for thermoplastic applications, thePVOH must usually be modified.

Modified PVOH is used in many different water-dispersible thermoformablearticles, such as fibers, films and fabrics which maintain theirintegrity and strength when in use, but dissolve and disperse whenplaced in contact with water. Unmodified PVOH is used in industry formany different solution-based applications and is not generallyconsidered to be thermoformable or melt-processable. Some suchapplications for unmodified PVOH include warp sizing in textiles, fabricfinishing, adhesives, paper processing additives, andemulsifiers/dispersants.

The prior art has demonstrated some success in modifying PVOH for use inthermoplastic applications. By “modified” PVOH, it is meant PVOH resinwhich has been chemically modified, including PVOH having anothercompound grafted thereto, or PVOH resin that has been mixed with one ormore plasticizers. In each instance, these “modifications” have beenneeded to permit PVOH to be used in thermoformable articles.

To overcome the thermoplastic processing problems, chemically modifiedPVOH has been used. Some prior art teachings have used ethers of PVOH,ethoxylated PVOH or lacton-modified PVOH to produce thermoformablearticles.

The prior art has also used PVOH that has not been modified structurallyby adding a plasticizing agent to the PVOH which permits the PVOH to beextruded into films and fibers. Examples of plasticizers include water,ethylene glycol, glycerin and ethanolamine.

However, there are problems associated with the addition of plasticizersto PVOH. One of the most pronounced problems during processing is thefogging of the volatile plasticizer during the melt extrusion andcondensing of vapor and effects of the vapor to the operatingenvironment. In addition, the extruded articles such as films or fiberslose the plasticizers since the plasticizer molecules diffuse out of thefilm or fibers. This causes the films or fibers to become brittle overtime and often causes the article to fail.

Additionally, films and fibers including modified PVOH or PVOH and aplasticizer may be limited in their utility. These films and fibers maybe too stiff to be used for certain applications. Additionally, thetexture of the films may not be soft enough for comfortable contact withthe skin of an individual.

Accordingly, what is needed is an unmodified PVOH that may be used inblend compositions that are thermoplastically formed into films andfibers. These films and fibers may then be used in the production ofwater-dispersible, flushable articles without the use of plasticizingagents. These fibers, films and fabrics could be used in products suchas personal care products, diapers, feminine napkins and pads, trainingpants, wipes, adult incontinence products, release liners, productpackaging, etc., which contain the above-mentioned fibers, films andfabrics. Additionally, what is needed are methods of makingthermoplastic films and fibers that have enhanced softness andductility.

SUMMARY OF THE INVENTION

Accordingly, the present invention desires to produce films and fibersincluding blend compositions having unmodified PVOH and a metallocenepolyolefin or grafted metallocene polyolefin.

Another desire of the present invention is to use unmodified PVOH and ametallocene polyolefin or grafted metallocene polyolefin to form filmsand fibers without the use of a plasticizing agent.

These and other desires are satisfied by the present invention. Thepresent invention discloses the selection and use ofcommercially-available grades of PVOH for thermoplastic applications.“Thermoplastic” is defined, herein, as a resin which can be melted andeasily extruded to form a desired article, i.e., the material is meltprocessable. These commercially-available grades of PVOH are combinedwith a metallocene polyolefin or grafted metallocene polyolefin toprovide a blend composition useful in the production of films and fibersthat have enhanced softness and ductility.

PVOH is a commodity polymer, commonly used in aqueous solution-basedapplications. Since it is a commodity polymer, thermoplastic articlesmade using unmodified PVOH are generally less expensive than articlesmade using modified PVOH due to the additional process steps required tomodify the PVOH. Also, unmodified PVOH is, in general, less expensivethan other water-soluble polymers.

In its unmodified form, PVOH has not been used for thermoplasticapplications. Typically, some modification of the PVOH, such as chemicalgrafting or addition of plasticizer, is necessary to achieve meltprocessability for PVOH. In the present invention, a window ofthermoplastic processability has been discovered and defined forunmodified, commercially-available PVOH, according to: 1) thecomposition or % hydrolysis of the PVOH, 2) the molecular weight of thePVOH, 3) the solution viscosity of the PVOH, or 4) the melt viscosity ofthe PVOH. The selected grades of PVOH have demonstratedthermoplasticity, allowing for continuous, melt extrusion or conversioninto thin films in a continuous, extrusion process.

These grades of PVOH are also useful for melt spinning of fibers,injection molding or other thermoplastic applications. Extruded films ofthe unmodified PVOH/metallocene polyolefin or grafted metallocenepolyolefin blends described herein have very high strength and modulus,excellent clarity, and fast crystallization and solidification rates.The advantages of melt processing a thermoplastic, unmodified PVOH intoa useful, strong, clear, water-soluble article are evident. Meltprocessing is a desirable thermoforming process compared to solutionprocessing. Melt processing eliminates the need to add steps such aschemical grafting, addition of a plasticizer, or other modification inorder to achieve melt processability.

These grades of PVOH may be mixed with additional polymers, such asmetallocene polyolefins or grafted metallocene polyolefins, to providedesired characteristics to the films and fibers, such as enhancedductility and enhanced softness.

DETAILED DESCRIPTION

PVOH is generally produced by a two step process as shown in Scheme 1.Since vinyl alcohol is not a stable monomer, the polymerization of vinylalcohol is not an option for making PVOH. Instead, the process utilizesa readily available monomer, vinyl acetate, as the starting point. Thefirst step is the polymerization of vinyl acetate into polyvinyl acetate(PVA). The second step is the hydrolysis or alcoholysis of PVA into acopolymer of vinyl acetate and vinyl alcohol, or polyvinyl alcohol(PVOH). Depending on the hydrolysis level as defined in the equation inScheme 1, a wide range of PVOH copolymers can be produced when thehydrolysis reaction is allowed to reach certain conversion levels.

For PVOH, the degree of hydrolysis is controlled during the alcoholysisreaction and is independent of the control of the molecular weight ofthe PVOH formed. Fully hydrolyzed PVOH is obtained if alcoholysis isallowed to go to completion. The reaction is terminated by removing orneutralizing the sodium hydroxide catalyst used in the process.Typically, a small amount of water is added to the reaction vessel topromote the saponification reaction of PVA. The extent of hydrolysis isinversely proportional to the amount of water added. The alcoholysis canbe carried out in a highly agitated slurry reactor. A fine precipitateforms as PVA, which is then converted to PVOH. The PVOH product is thenwashed with methanol and is filtered and dried to form a white, granularpowder.

The molecular weight of the PVOH is controlled by the polymerizationcondition of vinyl acetate. Many properties of PVOH depend on the degreeof hydrolysis and the molecular weight. As the molecular weightincreases, the solution viscosity, tensile strength, water resistance,adhesive strength, and solvent resistance increase. As molecular weightdecreases, the flexibility, water solubility, and ease of solvationincrease. As the degree of hydrolysis increases, the water resistance,tensile strength, block resistance, solvent resistance, and adhesion topolar substrates increase. As the degree of hydrolysis decreases, thewater solubility, flexibility, water sensitivity and adhesion tohydrophobic substrates increase.

Due to the strong dependence of PVOH on the molecular weight and degreeof hydrolysis, PVOH is typically supplied in combination of these twoparameters. PVOH is classified into 1) partially hydrolyzed (87.0 to89.0% hydrolysis); 2) intermediately hydrolyzed (95.5 to 96.5%hydrolysis); 3) fully hydrolyzed (98.0 to 98.8% hydrolysis); and 4)super hydrolyzed (>99.3% hydrolysis). Within each category of PVOH, theresin is differentiated by solution viscosity, measured at 4% solutionin water at 20° C. in centipoise. The viscosity is used as a molecularweight measure since solution viscosity is typically related to themolecular weight by the well known Mark-Houwink equation:

η=KM _(v) ^(a)

wherein

η=intrinsic viscosity

K=constant (dependent upon the polymer)

M_(v)=molecular weight

a=factor based on the rigidity of the polymer chains and is dependent onthe polymer.

For unmodified PVOH, it was known that higher molecular weight gradeswere not thermoplastic. It was surprising that unmodified PVOH at lowermolecular weights would be thermoplastic based on the non-meltprocessability of higher molecular weights grades. Unmodified PVOH withweight average molecular weight as low as 8750 g/mole was discovered tobe thermoplastic and melt processable, with high melt strength,excellent film strength and great clarity. Typically, a polymer withsuch a low starting molecular weight would not be expected to be meltprocessable into a useful material.

Additionally, it was discovered that the melt viscosity of the PVOHgrades could be used to determine which grades of PVOH werethermoplastic. In general, those grades having a melt viscosity lessthan about 1500 Pa·s at a shear rate of 500 s⁻¹ were determined to bemelt processable.

Not all grades of PVOH were discovered to be thermoplastic. The PVOHgrades useful in this invention desirably have a solution viscosity ofless than about 10 cp in a 4% water solution at 20° C. and a hydrolysisof less than about 90%. Examples of commercially-available grades ofPVOH useful in this invention are ELVANOL® 51-05 from DuPont(Wilmington, Del.), AIRVOL® 203 and 205 from Air Products and Chemical,Inc. (Allentown, Pa.), and GOHSENOL® KP-06 from Nippon Gohsei (Japan).PVOH is typically sold in powder or granule form, however pellets orother forms of resin can be used in this invention since the physicalform of PVOH does not affect melt processability.

Metallocene polyolefins (mPO) are the polyolefins manufactured bypolymerizing olefinic monomers by metallocene catalysts. The metallocenepolyolefins have better controlled polymer microstructures than thepolyolefins manufactured by using conventional Ziegler-Natta catalysts,including narrower molecular weight distribution, well-controlledcomposition distribution, comonomer sequence distribution, andstereoregularity. Metallocene polyolefins include both the homo-polymersof ethylene, propylene, and alpha-olefins containing up to 20 carbonatoms and co-polymers thereof with other alpha-olefins and functionalmonomers. Examples of metallocene polyolefins include, but are notlimited to, the EXACT® polyolefins from Exxon Mobil Chemicals (Houston,Tex.) and AFFINITY® plastomers by Dow Chemical Company (Midland, Mich.).

Additionally, depending on the type of blend application for which thePVOH will be used, films or fibers, the exact processing characteristicsmay vary. For example, some of the thermoplastic grades may be bettersuited for the production of thermoplastic films while other grades maybe more useful for the production of fibers. The exact grade to use willdepend upon the item being made and the metallocene polyolefin orgrafted metallocene polyolefin that is blended with the PVOH.

The present invention uses these thermoplastic PVOH grades with anadditional compound to form blend compositions. These blend compositionsmay then be formed into thermoplastic articles such as films and fiberusing the methods of the present invention. The additional compound isused to enhance the properties of the resulting films and fibers. In thepresent invention, a metallocene polyolefin or grafted metallocenepolyolefin is used to help produce films that are softer and moreductile than films comprising PVOH alone. The present invention is ableto achieve these results even though PVOH and metallocene polyolefinsare generally incompatible. However, the metallocene polyolefins orgrafted metallocene polyolefins used in the methods of the presentinvention have improved compatibility with PVOH.

A variety of monomers may be useful in the practice of this invention.The term “monomer(s)” as used herein includes monomers, oligomers,polymers, mixtures of monomers, oligomers and/or polymers, and any otherreactive chemical species that are capable of covalent bonding with theparent polymer, metallocene polyolefins. Suggested monomers areethylenically unsaturated and contain a polar vinyl group. Such monomersare termed “polar vinyl” herein. A variety of polar vinyl monomers maybe useful in the practice of this invention. Monomer as used hereinincludes monomers, oligomers, polymers, mixtures of monomers, oligomersand/or polymers, and any other reactive chemical species that is capableof covalent bonding with the parent polymer, metallocene polyolefin.Methods of grafting polyolefin compositions and particularly desirablegrafted-polyefin compositions are disclosed in U.S. patent applicationSer. No. 08/733,410 filed Oct. 18, 1996, now U.S. Pat. No. 6,707,405 thedisclosure of which is herein incorporated in its entirety. The methodsare applicable to mPO as well.

Ethylenically unsaturated monomers containing a polar functional group,such as hydroxyl, carboxyl, amino, carbonyl, halo, thiol, sulfonic,sulfonate, etc. are appropriate for this invention and are desired.Ethylenically unsaturated polar monomers include 2-hydroxyethylmethacrylate (hereinafter HEMA), poly(ethylene glycol) methacrylates(hereinafter PEG-MA) including poly(ethylene glycol) ethyl ethermethacrylate, poly(ethylene glycol) acrylates, poly(ethylene glycol)ethyl ether acrylate, poly(ethylene glycol) methacrylates with terminalhydroxyl groups, acrylic acid, maleic anhydride, itaconic acid, sodiumacrylate, 3-hydroxypropyl methacrylate, acrylamide, glycidylmethacrylate, 2-bromoethyl acrylate, carboxyethyl acrylate, methacrylicacid, 2-chloroacrylonitrile, 4-chlorophenyl acrylate, 2-cyanoethylacrylate, glycidyl acrylate, 4-nitrophenyl acrylate, pentabromophenylacrylate, poly(propylene glycol) methacrylate, poly(propylene glycol)acrylate, 2-propene-1-sulfonic acid and its sodium salt, sulfo ethylmethacrylate, 3-sulfopropyl methacrylate, and 3-sulfopropyl acrylate.

Desired ethylenically unsaturated monomers include acrylates andmethacrylates. Particularly desirable monomers, oligomers, polymers,mixtures of monomers, oligomers and/or polymers, and any other reactivechemical species which is capable of covalent bonding with the parentpolymer, metallocene polyolefin, ethylenically unsaturated monomerscontaining a polar functional group are 2-hydroxyethyl methacrylate(hereinafter HEMA) and poly(ethylene glycol) methacrylates (hereinafterPEG-MA). A particularly desirable poly(ethylene glycol) methacrylate ispoly(ethylene glycol) ethyl ether methacrylate. However, it is expectedthat a wide range of polar vinyl monomers would be capable of impartingsimilar effects as HEMA and PEG-MA to metallocene polyolefin (mPO) andwould be effective monomers for grafting. For grafting purposes, theamount of polar vinyl monomer relative to the amount of mPO may rangefrom about 0.05 to about 30 weight percent of monomer to the weight ofmPO. Desirably, the amount of monomer should exceed 0.1 weight percentto improve the processability of the mPO. A range of grafting levels isdemonstrated in the above-incorporated U.S. patent applications.Typically, the monomer addition levels were between 2.5 percent and 15percent of the weight of the base mPO resin. Ethylenically unsaturatedmonomers containing a polar functional group, such as hydroxyl,carboxyl, amino, carbonyl, halo, thiol, sulfonic, sulfonate, etc. areappropriate for this invention and are desired. Desired ethylenicallyunsaturated monomers include acrylates and methacrylates. It is expectedthat a wide range of polar vinyl monomers would be capable of impartingsimilar effects as HEMA and PEG-MA and would be effective monomers forgrafting.

This invention has been demonstrated in the following Examples by theuse of HEMA as the polar vinyl monomer. The HEMA was obtained fromAldrich Chemical Company and is designated Aldrich Catalog number12,863-5. The grafted mPE used in the following Examples was an EXACT®4151 metallocene polyethylene, grafted with 9 weight percent HEMA and0.13, 0.28, or 0.54 weight percent LUPERSOL® 101 initiator,respectively. The process temperature was 180° C. and the screw speedwas 300 rpm using the twin screw extruder set forth in Example 3,hereinbelow. PEG-MA is also a suggested monomer and can also be obtainedfrom Aldrich Chemical Company. A desirable PEG-MA is poly(ethyleneglycol) ethyl ether methacrylate, sold under the Aldrich Catalogdesignation number 40,954-5. Poly(ethylene glycol) ethyl ethermethacrylate is a derivative of poly(ethylene methacrylate). Thepoly(ethylene glycol) ethyl ether methacrylate sold by Aldrich under theabove designation number has a number average molecular weight ofapproximately 246 grams per mol. PEG-MA with a number average molecularweight higher or lower than 246 g/mol are also applicable for thisinvention. The molecular weight of the PEG-MA can range up to 50,000g/mol. However, lower molecular weights are preferred for fastergrafting reaction rates. The desired range of the molecular weight ofthe monomers is from about 246 to about 5,000 g/mol and the most desiredrange is from about 246 to about 2,000 g/mol. Again, it is expected thata wide range of polar vinyl monomers as well as a wide range ofmolecular weights of monomers would be capable of imparting similareffects to mPO resins and blends incorporating such grafted-mPE resinsand would be effective monomers for grafting and modification purposes.

A variety of initiators may be useful in the grafting of the mPO. Whengrafting is achieved by the application of heat and intensive mixing, asin a reactive-extrusion process, it is desirable that the initiatorgenerates free radicals through the application of heat. Such initiatorsare generally referred to as thermal initiators. For the initiator tofunction as a useful source of radicals for grafting, the initiatorshould be commercially and readily available, stable at ambient orrefrigerated conditions, and generate radicals at reactive-extrusiontemperatures.

Compounds containing an O—O, S—S, or N═N bond may be used as thermalinitiators. Compounds containing O—O bonds, peroxides, are commonly usedas initiators for polymerization. Such commonly used peroxide initiatorsinclude: alkyl, dialkyl, diaryl and arylalkyl peroxides such as cumylperoxide, t-butyl peroxide, di-t-butyl peroxide, dicumyl peroxide, cumylbutyl peroxide, 1,1-di-t-butyl peroxy-3,5,5-trimethylcyclohexane,2,5-dimethyl-2,5-di(t-butylperoxy)hexane,2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3 and bis(a-t-butylperoxyisopropylbenzene); acyl peroxides such as acetyl peroxides andbenzoyl peroxides; hydroperoxides such as cumyl hydroperoxide, t-butylhydroperoxide, p-methane hydroperoxide, pinane hydroperoxide and cumenehydroperoxide; peresters or peroxyesters such as t-butyl peroxypivalate,t-butyl peroctoate, t-butyl perbenzoate,2,5-dimethylhexyl-2,5-di(perbenzoate) and t-butyl di(perphthalate);alkylsulfonyl peroxides; dialkyl peroxymonocarbonates; dialkylperoxydicarbonates; diperoxyketals; ketone peroxides such ascyclohexanone peroxide and methyl ethyl ketone peroxide. Additionally,azo compounds such as 2,2′-azobisisobutyronitrile abbreviated as AIBN,2,2′-azobis(2,4-dimethylpentanenitrile) and1,1′-azobis(cyclohexanecarbonitrile) may be used as the initiator. Thisinvention has been demonstrated in the following Examples by the use ofa liquid, organic peroxide initiator available from Elf Atochem NorthAmerica, Inc. of Philadelphia, Pa., sold under the trade designationLUPERSOL® 101. LUPERSOL® 101 is a free radical initiator and comprises2,5-dimethyl-2,5-di(t-butylperoxy) hexane. Other initiators and othergrades of LUPERSO® initiators may also be used, such as LUPERSOL® 130.

The grafting of mPO may be performed in a continuous reaction device,such as an extruder. A twin screw extruder is preferred for graftingpolar monomers onto mPO due to its high intensity of dispersive anddistributive mixing. The level of grafting of mPO ranges from about 1 toabout 30% by weight. Desirably, the level of grafting is from about 2 toabout 20% by weight. Even more desirably, the level of grafting is fromabout 3 to about 15% by weight.

The blends including thermoplastic PVOH grades and a metallocenepolyolefin or grafted metallocene polyolefin may be extruded using mostknown extruding devices. In general, while a thermoplastic film may beextruded at extrusion temperatures above the melting point of thePVOH/metallocene polyolefin blend, it is preferred to use extrusiontemperatures near the melting point as the resulting films and fibersare generally clearer, have fewer imperfections, are more ductile andstronger, and can be drawn into much thinner films.

As discussed earlier, the films and fibers made by the methods of thepresent invention can be extruded from unmodified PVOH/metallocenepolyolefin blends without the use of a plasticizer. Many differentplasticizers are known, including, for example, ethylene glycol,glycerines and ethanolamine. In addition to these plasticizers, water isalso known to be used as a plasticizer in the production of PVOH filmsand fibers. However, these plasticizers, including water, have severaldisadvantages when used in the production of films and fibers. Ingeneral, plasticizers, including water, will slowly diffuse out of aPVOH film or fiber causing the film or fiber to become lucid and brittleand therefore more likely to break or shatter.

Additionally, plasticizers, including water, added to PVOH may causebubbling of the filmri during the extrusion process. This is especiallytrue with water. Therefore, care must be taken prior to the blendingwith a metallocene polyolefin or grafted metallocene polyolefin andproduction of the film to ensure that the PVOH powder or pellets remainsubstantially water-free. This helps to ensure that the films and fibersproduced by the methods of the present invention are also substantiallywater-free. By “substantially water-free” it is meant that the films andfibers produced using the methods of the present invention contain lessthan about 2.0 percent by weight of water. Desirably, the films andfibers contain less than about 1.0 percent by weight of water. Moredesirably, the films and fibers contain less than 0.5 percent by weightof water.

The importance of this invention is that PVOH/metallocene polyolefinblends have been discovered that may be directly extruded into awater-soluble, thin film without the need for any chemical modificationof the PVOH or the addition of a plasticizer. The elimination of anychemical modification of the PVOH eliminates the labor intensive step ofchemically modifying or grafting the PVOH. The elimination of aplasticizer admixed with the PVOH relieves the common problems involvedwith plasticizers as previously discussed. The water-soluble film madeby the present invention will keep its original properties and in-useperformance unlike a PVOH/metallocene polyolefin film containing aplasticizer which will become brittle over time.

One additional advantage in the production of water-soluble productsfrom the PVOH/metallocene polyolefin films and fibers is in the productconverting stage. PVOH has a higher melting point than many otherwater-soluble polymer systems used for making water-dispersible,flushable articles, including, for example, polyethylene oxide-basedmaterials. PVOH film can withstand heat from a hot-applied melt adhesivewhich may be used during product construction. In contrast, PEO-basedmaterials have limitations in this aspect due to the low meltingtemperature of the PEO of about 60 to 70° C. Therefore, thePVOH/metallocene polyolefin films and fibers made by the presentinvention have great usefulness in the production of water-dispersible,flushable products.

The PVOH/metallocene polyolefin blends, films and fibers made by themethods of the present invention include a metallocene polyolefin orgrafted metallocene polyolefin that enhances certain characteristics ofthe films and fibers when compared to films and fibers comprising onlyunmodified PVOH. The metallocene polyolefin or grafted metallocenepolyolefin imparts improved softness and ductility to the film. Thesefeatures are very useful for films that are used in a personal carearticle, such as a diaper, feminine article, incontinence device, amongothers.

The amount of metallocene polyolefin or grafted metallocene polyolefinthat may be used is in the amount of from about 1 to about 99% by weightof the PVOH/metallocene polyolefin blend. Desirably, the methods of thepresent invention use a blend comprises from about 50 to about 90% byweight PVOH and from about 50 to about 1% metallocene polyolefin orgrafted metallocene polyolefin. Even more desirably, the blend comprisesfrom about 65 to about 80% by weight PVOH and from about 35 to about 20%metallocene polyolefin or grafted metallocene polyolefin.

The present invention is further illustrated by the following examples,which are not to be construed in any way as imposing limitations uponthe scope thereof. On the contrary, it is to be clearly understood thatresort may be had to various other embodiments, modifications, andequivalents thereof which, after reading the description herein, maysuggest themselves to those skilled in the art without departing fromthe spirit of the present invention and/or the scope of the appendedclaims.

EXAMPLE 1

The melt processability of PVOH was first demonstrated by a twin-screwextrusion process. A Haake (Paramus, N.J.) TW-100 counter-rotatingtwin-screw extruder, fitted with a 4″ cast film die was used. Theextruder had a length of 300 mm. Each conical screw had a diameter of 30mm at the feed port and a diameter of 20 mm at the die. A grade ofrelatively low degree hydrolysis from Nippon Gohsei, GOSHENOL® KP-06,was selected. This PVOH resin was manufactured for use as a dispersionagent for use in aqueous solution applications. It was not intended formelt processing. The degree of hydrolysis is 71-74%, it's viscosity in a4% solution in water at 20° C. is 5 to 7 cp, as measured by Hoepplerfalling ball method. It is supplied as a white granulate powder. To testthe possibility for thermoplastic process, the resin was fed to theHaake twin-screw extruder directly without pelletization.

An extruded film was collected by a chilled wind-up roll. Initially, thescrew speed was set at 134 rpm. The barrel temperatures were 150, 185,185 and 190° C. for zones 1, 2, 3 and 4 (die) respectively. Due tointensive shear heating, the melt temperature was raised above the settemperature of the film die, reaching about 225° C. Under theseconditions, it was surprising that a thick film of about 4-6 mil couldbe produced from this resin which is supposed to be non-thermoplastic.However, the quality of the film was poor and there were many holes inthe film. The films were relatively hazy and not as clear at typicalPVOH films. The film was extremely rigid and brittle. On the film therewere many deep flow lines visually observable. The melt strength of PVOHunder these conditions was weak. The PVOH film made under thistemperature was discolored and appeared slightly yellowish.

EXAMPLE 2

In Example 2, the same PVOH resin used in Example 1 was tested todetermine whether the film processing conditions could be improved.First, the extrusion temperature profile was modified. The barreltemperatures were set at 150, 185, 185 and 180° C. for zones 1, 2, 3 and4 (die) respectively. The screw speed was maintained at 134 rpm. Thislower die set temperature brought down the melt temperature to about 195to 200° C. Surprisingly, as the melt temperature of the PVOH dropped,the film properties improved dramatically. At a melt temperature ofabout 195 to 200° C., the melt strength of PVOH improved greatly suchthat a PVOH film could be drawn down to less than 0.2 mil. In contrastto the hazy appearance of the PVOH made in Example 1, the PVOH film madein this example under the lower melt temperature had excellent clarityand was essentially free of film defects.

Compared to the PVOH film in Example 1, the film made at a lowertemperature had greater strength and softness. The tensile properties ofthe pellet-derived PVOH film were tested on a Sintech 1/D tensile testeravailable from MTS Systems Corp. (Machesny Park, Ill.). The PVOH filmhad a high melt strength such that the winding up of the film at highspeed did not cause any tearing or breaking of the PVOH film. The peakstress of the film was over 60 MPa. The elongation-at-break of the PVOHwas about 73%. The modulus of the film was also high, slightly over 1800MPa.

EXAMPLE 3

The same PVOH resin used in Example 1 was used for this example. PVOH isusually delivered from the manufacture in a powdered form. Sincepolymers in the pellet form are generally easier to work with, anexperiment was devised to see if cast film created directly from PVOHpowder had different tensile properties that those created from PVOH inthe pellet form. PVOH pellets were made by extruding PVOH powder on aWerner & Pfleiderer (Ramsey, N.J.) ZSK-30 extruder at 20 lb/hr and 300rpm. The ZSK-30 extruder has a pair of co-rotating screws arranged inparallel with the center-to-center distance between the shafts of thetwo screws at 26.2 mm. The nominal screw diameters are 30 mm. The actualouter diameters of the screws are 30 mm and the inner screw diametersare 21.3 mm. The thread depths are 4.7 mm. The length of the screws are1328 mm and the total processing section length was 1338 mm. This ZSK-30extruder had 14 processing barrels which were numbered consecutively 1to 14 from the feed barrel to the die. The first barrel was not heated,but cooled by water. Barrels 2 to 14 were divided into 7 zones. Barrels2 and 3 comprised zone 1. Barrels 4 and 5 comprised zone 2. Barrels 6and 7 comprised zone 3. Barrels 8 and 9 comprised zone 4. Barrels 10 and11 comprised zone 5. Barrels 12 and 13 comprised zone 6. Barrel 14 (die)comprised zone 14. The extruded melt strands were cooled by air on a 15foot conveyer belt equipped with fans, and then pelletized. As a rule ofthumb, it was expected that the films from pellets would have lowertensile strength than the powder-derived films since the PVOH resinsuffers from additional thermomechanical degradation during the extrapass through the extruder.

However, the PVOH pellets made on the ZSK-30 twin-screw extruder hadexcellent cast film processability. Thin films were easily made from thepellets on the same Haake twin-screw film cast line used in Example 1.The barrel temperatures were set at 180, 190, 190 and 180° C. for zones1, 2, 3 and 4 (die) respectively. The screw speed was maintained at 134rpm. This film also crystallized very quickly. High qualitywater-soluble film was again made using the temperature profile setforth in Example 2.

The tensile properties were tested under the same conditions as setforth in Example 2. It was found that the pellet-derived film wasslightly stronger than that powder-derived film. The pellet-derived filmwas also slightly more rigid and slightly less ductile than thepowder-derived film.

The peak stress of the pellet-derived film is nearly twice that of thepowder-derived film, reaching a high value of 120 MPa versus a 60 MPafor the powder-derived film. The modulus of the pellet-derived film wasabout 30% higher than the powder-derived film, reaching 2580 MPa, whilethe powder film had a modulus of 1800 MPa. The powder-derived film was alittle more ductile giving slightly higher elongation-at-break. Due tothe peak stress and its contribution to the film's overall tensiletoughness as measured as the area under the tensile curve, thepellet-derived PVOH film had a 50% higher toughness than thepowder-derived PVOH film.

PVOH film produced from the PVOH pellets was determined to be strongerand tougher than powder-derived PVOH film. Unexpectedly, it showed anupgrade in tensile properties by subjecting the PVOH through morethermal processing. Typically, as a polymer is subjected to morethermomechanical stress, polymer degradation occurs which results in theloss of mechanical and other properties.

EXAMPLES 4-6

Next, three grades of PVOH from Air Products at fully and superhydrolyzed level, i.e. 98.8—98.8% and +99.3% hydrolysis were selected todetermine whether they exhibited thermoplastic properties. Since allthree grades had a high degree of hydrolysis, the three resins wereselected based upon viscosity. The three grades were resins of low,medium and high viscosity. These grades ensured that the correlationbetween hydrolysis and molecular weight on thermoplastic processingcould be determined. Representing these three grades were Air ProductsAIRVOL® 107, 125, and 165 of respectively low, medium and high solutionviscosities (See Table 1). When these three grades of PVOH were extrudedon the Haake extruder used in Example 1, it was discovered that none ofthese grades could be extruded similar to that of Nippon KP-06. ThesePVOH resins caused the extruder to plug up. When the ZSK-30 extruderused in Example 3 was used, the same problems occurred. Therefore, PVOHfilms using PVOH having a high degree of hydrolysis could not beextruded, regardless of the viscosity of the resin.

EXAMPLES 7-17

Next, a broader comparison was done to determine the correlation ofhydrolysis and viscosity of a particular PVOH resin versus thethermoplastic capability of the resin. In addition to the PVOH resinsused in Examples 1 and 4 to 6, four other grades of AIRVOL® resin wereused (AIRVOL® 203, 205, 523 and 540) along with three grades of DuPontELVANOL® resin (ELVANOL® 51-05, 52-22 and 50-42). The four AIRVOL® andthree ELVANOL® resins all are partially hydro lyzed (having a hydrolysisof between about 87 to about 90 percent), but varied viscosities. Table1 is a chart of solution viscosity versus percent hydrolysis accordingto vendor data, for the selected grades of PVOH.

TABLE 1 Viscosity 4% solution, Manufacturer Trade Name % Hydrolysis 20°C. Nippon Gohsei KP-06 71-74 5-7 Air Products AIRVOL ® 125 99.3+ 26-30AIRVOL ® 165 99.3+ 55-65 AIRVOL ® 107 98.0-98.8 5.4-6.5 AIRVOL ® 20387.0-89.0 3-4 AIRVOL ® 205 87.0-89.0 5-6 AIRVOL ® 523 87.00-89.0  22-26AIRVOL ® 540 87.0-89.0 40-50 DuPont ELVANOL ® 51-05 87.0-89.0 3-4ELVANOL ® 52-22 87.0-89.0 22-26 ELVANOL ® 50-42 87.0-89.0 40-50

Each of the above grades of PVOH were extruded on a Werner & PfleidererZSK-30 twin-screw extruder in order to determine melt processability.

It was not obvious to tell which grades of PVOH would demonstratethermoplasticity from the percent hydrolysis and/or the solutionviscosity. Of the eleven resins studied, only four grades of PVOH weredetermined to have thermoplastic processability: NG KP-06, ELVANOL®51-05, AIRVOL® 205, and AIRVOL® 203. The melt strands of the KP-06strands were colorless, the AIRVOL® grades were slighty yellow colored,and the ELVANOL® grade was yellow. For each of the four resins, the meltstrands were transparent. The strands appeared very strong and brittle.

All of the other grades of PVOH were determined to not bethermoplastically processable. The extruded PVOH for thenon-thermoplastic grades was severely discolored, due to thermaldegradation. The strands had severe melt fracture, breakage, and/orbubble formation. After several minutes of extrusion, the degraded PVOHwould begin to plug the die holes and the percent torque and pressurewere observed to increase beyond the normal, safe operating range. ThePVOH would spit and/or pop out of the die or no material would extrudeat all, and the PVOH would begin to bridge at the feed throat. In somecases, the non-melt processable grades of PVOH would “freeze” and lockup the screws, triggering the extruder to shut off due to percent torqueoverload. The observed problems with extruding the non-thermoplasticgrades of PVOH made the observation of the melt processable,thermoplastic grades of PVOH even more remarkable.

Table 2 shows the average extrusion data for each of the thermoplasticgrades of PVOH and two of the non-thermoplastic grades of PVOH, ELVANOL®52-22 and AIRVOL® 523, before the die holes were plugged.

TABLE 2 BARREL TEMPERATURE Zone 7 Melt Die Feed Rate Screw Speed 1 2 3 45 6 Temp Temp Pres Trade Name (lb/hr) (rpm) % Torque (° C.) (° C.) (°C.) (° C.) (° C.) (° C.) (° C.) (° C.) (PSI) THERMOPLASTIC KP-06 20.00301 39.00 179 181 180 180 180 180 192 203 270 AIRVOL ® 205 20.04 30044.15 178 180 180 180 180 181 188 200 484 ELVANOL ® 51-05 19.79 30041.75 178 180 181 180 180 180 192 203 446 AIRVOL ® 203 20.02 299 42.78181 180 179 180 175 180 182 199 183 NON-THERMOPLASTIC AIRVOL ® 523 19.99300 54.95 178 180 179 182 181 181 199 213 1386 ELVANOL ® 52-22 20.01 30155.09 181 180 179 180 180 180 198 218 1511

As shown in Table 2, the melt processable, thermoplastic grades hadlower percent torque (at least 20% lower), melt temperature (at least10° C. lower), and die pressure (over 65% lower), compared to thenon-thermoplastic grades. Thus, the qualitative observation of meltprocessability was confirmed by extrusion data.

Extruded pellets produced on the ZSK-30 extruder from each of thethermoplastic grades of PVOH were also converted into thin film on theHaake extruder, following the same procedure used for Example 3. NGKP-06 appeared to show the best film processability, in terms ofclarity, melt strength, and uniformity (with no visible gels). ELVANOL®51-05 produced a very thin film (down to less than 0.2 mil) withexcellent clarity. However, ELVANOL® 51-05 was not as “clean” as theKP-06 as shown by a few visible gels in the film. AIRVOL® 203 and 205produced very thin films (drawn down to about 0.5 mil) with less claritythan NG KP-06 or ELVANOL® 51-05. The Air Products resins were even less“clean” with several gels in the film. The gels in the film for AIRVOL®grades made it more difficult to draw down to less than 0.5 mil, becauseof splitting due to gels.

The non-thermoplastic grades of PVOH, in either powder or extrudedpellet form, could not be converted into film on the Haake extruderfollowing the same procedure used for Example 3. No thin film could beproduced for any of the non-melt processable grades. Severediscoloration and die pressure were observed. For some grades, totallyblack sheets of thick rigid plastic were produced. After severalminutes, the thin slit in the film die plugged and no thin film could becollected.

EXAMPLES 18-27

In addition to hydrolysis, the commercial grade PVOH resins were testedto determine whether or not the molecular weight of the PVOH could beused to determine whether that particular resin was melt processable.The NG KP-06 resin, along with several of the AIRVOL® and ELVANOL®resins were used. Gel permeation chromatography (GPC) results (obtainedfrom American Polymer Standard Corporation, Mentor, Ohio) for thenumber-average molecular weight (M_(n)), the weight-average molecularweight (M_(w)) and the Z-average molecular weight (M_(z)) of the PVOHresins, in either powder or pellet form, are shown in Table 3.

TABLE 3 Poly- disperity Trade Name Form M_(n) M_(w) M_(z) (M_(w)/M_(n))MELT PROCESSABLE KP-06 powder 5,150 8,750 12,800 1.71 AIRVOL ® 205powder 25,000 46,500 74,450 1.86 ELVANOL ® 51-05 powder 22,350 45,85075,900 2.05 AIRVOL ® 203 powder 18,400 32,500 49,300 1.77 KP-06 pellets7,100 10,850 15,000 1.53 AIRVOL ® 205 pellets 30,750 52,400 85,700 1.70ELVANOL ® 51-05 pellets 27,650 51,950 85,000 1.88 AIRVOL ® 203 pellets22,550 36,800 54,450 1.63 NOT MELT PROCESSABLE AIRVOL ® 523 pellets61,900 148,300 296,900 2.40 ELVANOL ® 52-22 pellets 55,900 143,400302,000 2.57

The thermoplastic grades of PVOH powder had an average M_(w) rangingfrom 8,750 g/mole to 46,500 g/mole and M_(w)/M_(n) ranging from 1.71 to2.05. The same grades of PVOH, after extrusion and pelletizing on theZSK-30 extruder, retained thermoplasticity and film processability. Theextruded pellets had an average M_(w) ranging from 10,850 g/mole to52,400 g/mole and M_(w)/M_(n) ranging from 1.63 to 1.88. Thenon-thermoplastic grades of PVOH, however, had significantly higherM_(w) at 148,300 and 143,400 and higher M_(w)/M_(n) at 2.40 and 2.57.

Interestingly, after twin-screw extrusion, the M_(w) of the meltprocessable grades of PVOH increased and the M_(w)/M_(n) decreased.Typically, after extrusion, a polymer would have been expected toundergo degradation, resulting in reduced M_(w) and increasedM_(w)/M_(n).

EXAMPLES 28-39

Finally, the commercial grade PVOH resins were tested to determinewhether or not the melt viscosity of the PVOH could be used to determinewhether that particular resin was melt processable. Again, the NG KP-06resin, along with several of the AIRVOL® and ELVANOL® resins were used.At a shear rate of 500 s⁻¹, the apparent melt viscosity of thethermoplastic and non-thermoplastic grades of PVOH were significantlydifferent. Table 4 shows the apparent melt viscosity at a shear rate of500 s⁻¹ for PVOH powder and pellets produced on the ZSK-30 extruder.

TABLE 4 Trade Name Form Melt Viscosity (Pa · s) MELT PROCESSABLE KP-06powder 717 KP-06 pellets 686 ELVANOL ® 51-05 powder 796 ELVANOL ® 51-05pellets 1337 AIRVOL ® 203 powder 311 AIRVOL ® 203 pellets 490 AIRVOL ®205 powder 821 AIRVOL ® 205 pellets 1034 NOT MELT PROCESSABLE AIRVOL ®523 powder 4010 ELVANOL ® 52-22 powder 1684 ELVANOL ® 50-42 powder 2943ELVANOL ® 52-22 pellets 2508

Unmodified PVOH with a melt viscosity greater than about 1500 Pa·s wasnot melt processable and grades with a melt viscosity less than 1500Pa·s were melt processable.

As can be seen from the above examples, not all grades of commerciallyavailable PVOH resins are melt processable. In fact, only four of theeleven grades tested exhibited thermoplastic characteristics. However,by using the hydrolysis, the molecular weight, the solution viscosity orthe melt viscosity of the PVOH resins, it is possible to determine whichgrades of PVOH are likely to be melt processable.

However, due to the current number and type of PVOH grades, it isdifficult to determine the exact ranges of melt processability for allpotential PVOH resins. For the current grades, it is possible todetermine the hydrolysis, the molecular weight and the solutionviscosity for those grades which definitely are melt-processable, andfor those grades which are not melt processable. However there is amiddle area for these parameters for which no grades of PVOH arecurrently available.

For example, while partially hydrolyzed PVOH resins (less than 90percent) and fully hydrolyzed resins (greater than 95 percent) areavailable, there are no commercially available resins in between (having90 to 95 percent hydrolysis). Therefore, it is difficult to determinethe exact ranges of melt processability for all unmodified PVOH resinsbased on the percent hydrolysis. Additionally, grades of PVOH having aweight-average molecular weight of less than 60,000 are meltprocessable, while grades having a weight-average molecular weightgreater than 140,000 are not melt processable. Therefore, it isdifficult to determine the exact ranges of melt processability for allunmodified PVOH resins based on the weight-average molecular weight.Finally, for solution viscosity, grades having a solution viscosity lessthan 10 cp are melt processable while grades having a solution viscositygreater than 20 cp are not, leaving the range from 10-20 cp uncertain.However, it is possible to determine the exact range of meltprocessability using melt viscosity. Those grades having a meltviscosity less than about 1500 Pa·s are melt processable while gradeshaving a melt viscosity greater than about 1500 Pa·s are not meltprocessable.

EXAMPLE 40

A blend of 80% by weight of PVOH and 20% by weight of a graftedmetallocene polyethylene (mPE) was prepared. The PVOH was ELVANOL® 51-05from DuPont. The grafted mPE was EXACT® 4151 metallocene polyethylene(Exxon Mobil Chemicals; Houston, Tex.) grafted with 9% by weight of2-hydroxyethyl methacrylate (HEMA). The PVOH powder was fed to acounter-rotating twin-screw extruder TW-100 (manufactured by Haake;Paramus, N.J.) at a rate of 4 lb/hr by a twin-screw gravimetric feeder(manufactured by K-TRON; Pitman, N.J.). The grafted mPE was fed to thesame extruder at a rate of 1 lb/hr. The extruder had a screw length of300 mm. A strand die (manufactured by Haake) was used to make pelletsfrom the PVOH/grafted mPE blend. Each conical screw had a diameter of 30mm at the feed port and a diameter of 20 mm at the die. The extruder hadfour heating zones which were set at 170° C., 180° C., 180° C. and 190°C. respectively. The screw speed was 150 rpm. The resulting strands werecooled by air on a conveyor belt and subsequently pelletized using aConair Pelletizer (Bay City, Mich.).

Cast film of the PVOH/grafted mPE blend was made using the same TW-100twin-screw extruder fitted with a 4 inch cast film die (manufactured byHaake). The extruder temperatures were set at 170° C., 180° C., 180° C.and 175° C. respectively for the four zones starting from the feedingsection. The screw speed was 40 rpm. The film was collected from a filmwind-up device. The films made using these blends were translucent andthin.

The tensile tests of the forms made from the blend of polyvinyl alcoholand the grafted mPE were performed on a Sintech 1/D tensile testeravailable from MTS Systems Corp., Machesny Park, Ill. The film was cutinto a type V dogbone shape in accordance with ASTM D638. The test wasperformed with a grip separation of 30 mm and a crosshead speed of 4mm/second.

The resulting tensile properties of the PVOH/grafted mPE 80/20 blendfilms are shown in Table 5.

TABLE 5 80/20 PVOH/grafted PVOH control film mPE blend film Filmthickness (mil) 1.0 1.9 Peak Stress (MPa) 63 39 Strain-at-Break (%) 74116 Modulus (MPa) 1476 1155

As shown by the data in the table, the strain-at-break increased from74% to 116% and the tensile modulus decreased from 1476 to 1155 MPa,thereby showing improved ductility and softness.

EXAMPLE 41

A blend of 65% by weight of PVOH and 35% by weight of a graftedmetallocene polyethylene (mPE) was prepared. The PVOH was ELVANOL® 51-05from DuPont. The grafted mPE was EXACT® 4151 metallocene polyethylene(Exxon Mobil Chemicals; Houston, Tex.) grafted with 9% by weight of2-hydroxyethyl methacrylate (HEMA). The PVOH powder was fed to thecounter-rotating twin-screw extruder TW-100 used in Example 40 at a rateof 3.25 lb/hr by a twin-screw gravimetric feeder (manufactured byK-TRON; Pitman, N.J.). The grafted mPE was fed to the same extruder at arate of 1.75 lb/hr. The extruder had a screw length of 300 mm. A stranddie (manufactured by Haake) was used to make pellets from thePVOH/grafted mPE blend. Each conical screw had a diameter of 30 mm atthe feed port and a diameter of 20 mm at the die. The extruder had fourheating zones which were set at 170° C., 180° C., 180° C. and 190° C.respectively. The screw speed was 150 rpm. The resulting strands werecooled by air on a conveyor belt and subsequently pelletized using theConair Pelletizer of Example 40.

Cast film of the PVOH/grafted mPE blend was made using the same TW-100twin-screw extruder fitted with a 4 inch cast film die (manufactured byHaake). The extruder temperatures were set at 170° C., 180° C., 180° C.and 175° C. respectively for the four zones starting from the feedingsection. The screw speed was 40 rpm. The film was collected from a filmwind-up device. The films made using these blends were translucent andthin.

The tensile tests of the films made from the blend of polyvinyl alcoholand the grafted mPE were performed on the Sintech 1/D tensile tester.The film was cut into a type V dogbone shape in accordance with ASTMD638. The test was performed with a grip separation of 30 mm and acrosshead speed of 4 mm/second.

The resulting tensile properties of the PVOH/grafted mPE 65/35 blendfilms are shown in Table 6.

TABLE 6 65/35 PVOH/grafted PVOH control film mPE blend film Filmthickness (mil) 1.0 2.4 Peak Stress (MPa) 63 37 Strain-at-Break (%) 74100 Modulus (MPa) 1476 863

As shown by the data in the table, the strain-at-break increased from74% to 100% and the tensile modulus decreased from 1476 to 863 MPa,thereby showing improved ductility and softness.

Therefore, these results have shown that blends including unmodifiedPVOH and a metallocene polyolefin or grafted metallocene polyolefin maybe used in the absence of any chemical modification or grafting of thePVOH, or without the addition of any plasticizing agent or water toproduce quality thermoplastic films and fibers comprising a blend of thePVOH and the metallocene polyolefin or grafted metallocene polyolefin.The use of an unmodified PVOH in these blends avoids the additionalprocess steps associated with chemical modification or grafting of thePVOH and the problems associated with the use of plasticizers with thePVOH.

We claim:
 1. A method of making a substantially water-free thermoplasticarticle comprising: extruding a blend composition comprising from about1 to about 99% by weight of an unmodified polyvinyl alcohol and fromabout 99 to about 1% by weight of a metallocene polyolefin or graftedmetallocene polyolefin into the thermoplastic article.
 2. The method ofclaim 1, wherein a 4% in water solution of the unmodified polyvinylalcohol at 20° C. has a viscosity of less than about 20 centipoise. 3.The method of claim 2, wherein a 4% in water solution of the unmodifiedpolyvinyl alcohol at 20° C. has a viscosity of less than about 10centipoise.
 4. The method of claim 1, wherein the unmodified polyvinylalcohol has a hydrolysis of less than about 95%.
 5. The method of claim4, wherein the unmodified polyvinyl alcohol has a hydrolysis of lessthan about 90%.
 6. The method of claim 1, wherein the unmodifiedpolyvinyl alcohol has a weight-average molecular weight of less thanabout 140,000.
 7. The method of claim 6, wherein the unmodifiedpolyvinyl alcohol has a weight-average molecular weight of less thanabout 60,000.
 8. The method of claim 1, wherein the unmodified polyvinylalcohol has a melt viscosity at a shear rate of 500 s⁻¹ of less thanabout 1500 Pa·s.
 9. The method of claim 1, wherein the thermoplasticarticle has less than about 2.0 percent by weight of water.
 10. Themethod of claim 1, wherein the thermoplastic article has less than about1.0 percent by weight of water.
 11. The method of claim 1, wherein thethermoplastic article has less than about 0.5 percent by weight ofwater.
 12. The method of claim 1, wherein the metallocene polyolefin orgrafted metallocene polyolefin is selected from metallocenepolyethylene, 2-hydroxyethyl methacrylate grafted metallocenepolyethylene, or mixtures thereof.
 13. The method of claim 1, whereinthe grafted metallocene polyolefin is a graft copolymer of metallocenepolyolefin and at least one polar vinyl monomer is selected from thegroup consisting of 2-hydroxyethyl methacrylate, poly(ethylene glycol)methacrylates, poly(ethylene glycol) ethyl ether methacrylates,poly(ethylene glycol) acrylates, poly(ethylene glycol) ethyl etheracrylate, poly(ethylene glycol) methacrylates with terminal hydroxylgroups, acrylic acid, maleic anhydride, itaconic acid, sodium acrylate,3-hydroxypropyl methacrylate, acrylamide, glycidyl methacrylate,2-bromoethyl acrylate, carboxyethyl acrylate, methacrylic acid,2-chloroacrylonitrile, 4-chlorophenyl acrylate, 2-cyanoethyl acrylate,glycidyl acrylate, 4-nitrophenyl acrylate, pentabromophenyl acrylate,poly(propylene glycol) methacrylate, poly(propylene glycol) acrylate,2-propene-1-sulfonic acid and its sodium salt, sulfo ethyl methacrylate,3-sulfopropyl methacrylate, and 3-sulfopropyl acrylate.
 14. The methodof claim 1, wherein the metallocene polyolefin comprises a graftcopolymer of metallocene polyolefin and from about 1 to about 30 weightpercent of polar vinyl monomer, polar vinyl oligomer, polar vinylpolymer or a combination thereof.
 15. The method of claim 1, wherein thethermoplastic article comprises from about 50 to about 90% by weight ofan unmodified polyvinyl alcohol and from about 50 to about 10% by weightof a metallocene polyolefin or grafted metallocene polyolefin.
 16. Themethod of claim 1, wherein the thermoplastic article comprises fromabout 65 to about 80% by weight of an unmodified polyvinyl alcohol andfrom about 35 to about 20% by weight of a metallocene polyolefin orgrafted metallocene polyolefin.
 17. The method of claim 1, wherein thethermoplastic article is a film.
 18. The method of claim 1, wherein thethermoplastic article is a fiber.
 19. The method of claim 1, wherein thethermoplastic article is extruded at a temperature of less than about200° C.
 20. A method of making a thermoplastic article comprising:extruding a blend composition comprising from about 1 to about 99% byweight of an unmodified polyvinyl alcohol and from about 99 to about 1%by weight of a metallocene polyolefin or grafted metallocene polyolefininto the thermoplastic article, wherein the thermoplastic article hasless than about 2.0 percent by weight of water.
 21. The method of claim20, wherein a 4% in water solution of the unmodified polyvinyl alcoholat 20° C. has a viscosity of less than about 20 centipoise.
 22. Themethod of claim 21, wherein a 4% in water solution of the unmodifiedpolyvinyl alcohol at 20° C. has a viscosity of less than about 10centipoise.
 23. The method of claim 20, wherein the unmodified polyvinylalcohol has a hydrolysis of less than about 95%.
 24. The method of claim23, wherein the unmodified polyvinyl alcohol has a hydrolysis of lessthan about 90%.
 25. The method of claim 20, wherein the unmodifiedpolyvinyl alcohol has a weight-average molecular weight of less thanabout 140,000.
 26. The method of claim 25, wherein the unmodifiedpolyvinyl alcohol has a weight-average molecular weight of less thanabout 60,000.
 27. The method of claim 20, wherein the unmodifiedpolyvinyl alcohol has a melt viscosity at a shear rate of 500 s⁻¹ ofless than about 1500 Pa·s.
 28. The method of claim 20, wherein themetallocene polyolefin or grafted metallocene polyolefin is selectedfrom metallocene polyethylene, 2-hydroxyethyl methacrylate graftedmetallocene polyethylene, or mixtures thereof.
 29. The method of claim20, wherein the grafted metallocene polyolefin is a graft copolymer ofmetallocene polyolefin and at least one polar vinyl monomer is selectedfrom the group consisting of 2-hydroxyethyl methacrylate, poly(ethyleneglycol) methacrylates, poly(ethylene glycol) ethyl ether methacrylates,poly(ethylene glycol) acrylates, poly(ethylene glycol) ethyl etheracrylate, poly(ethylene glycol) methacrylates with terminal hydroxylgroups, acrylic acid, maleic anhydride, itaconic acid, sodium acrylate,3-hydroxypropyl methacrylate, acrylamide, glycidyl methacrylate,2-bromoethyl acrylate, carboxyethyl acrylate, methacrylic acid,2-chloroacrylonitrile, 4-chlorophenyl acrylate, 2-cyanoethyl acrylate,glycidyl acrylate, 4-nitrophenyl acrylate, pentabromophenyl acrylate,poly(propylene glycol) methacrylate, poly(propylene glycol) acrylate,2-propene-1-sulfonic acid and its sodium salt, sulfo ethyl methacrylate,3-sulfopropyl methacrylate, and 3-sulfopropyl acrylate.
 30. The methodof claim 20, wherein the metallocene polyolefin comprises a graftcopolymer of metallocene polyolefin and from about 1 to about 30 weightpercent of polar vinyl monomer, polar vinyl oligomer, polar vinylpolymer or a combination thereof.
 31. The method of claim 20, whereinthe thermoplastic article comprises from about 50 to about 90% by weightof an unmodified polyvinyl alcohol and from about 50 to about 10% byweight of a metallocene polyolefin or grafted metallocene polyolefin.32. The method of claim 20, wherein the thermoplastic article comprisesfrom about 65 to about 80% by weight of an unmodified polyvinyl alcoholand from about 35 to about 20% by weight of a metallocene polyolefin orgrafted metallocene polyolefin.
 33. The method of claim 20, wherein thethermoplastic article is a film.
 34. The method of claim 20, wherein thethermoplastic article is a fiber.
 35. The method of claim 20, whereinthe thermoplastic article is extruded at a temperature of less thanabout 200° C.